Methods of this type are used in particular for medical purposes in the field of computer radiography (CR). X-ray pictures in so-called storage phosphors are characterised here in that the X-ray radiation passing through an object, for example a patient, is stored as a latent picture in a storage phosphor layer. In order to read out the stored picture, the storage phosphor layer is irradiated with stimulation light, and so stimulated into emitting emission light, the intensity of which is dependent upon the respectively stored picture information. The emission light is collected by an optical detector and converted into electric signals which are further processed as required, and can be shown on a monitor or displayed on a corresponding display unit, such as a printer.
EP 1 319 963 A1, herein incorporated by reference in its entirety for background information only, describes a method wherein a detector is moved over a phosphor layer, whereby the emission light emitted from individual linear areas of the phosphor layer is collected. The collection of the emission light emitted from a linear area happens over an adjustable integration period. Due to the continuous feed of the detector during the integration period, the width of this area in the feed direction is determined by the integration period. In particular with low intensities of emission light, a longer integration period is set so as to increase the width of the linear areas. In this way the portion of so-called read-out noise on the detector signal is reduced, and consequently the signal/noise ratio can be improved.
It has, however, become apparent that a longer integration period does not lead to a better signal/noise ratio in all applications. On the contrary, in certain cases the noise can increase in relation to the signal of the emission light emitted over the integration period, and this results in an overall worse signal/noise ratio.
It is the aim of the invention to provide a method for reading out information stored in a phosphor layer whereby the signal/noise ratio is improved.